﻿<%@ page contentType="image/jpeg" import="java.awt.*,java.awt.image.*,java.util.*,javax.imageio.*" %>
<%!
Color getRandColor(int fc,int bc) {
		//给定范围获得随机颜色
		Random random = new Random();
		if(fc>255) fc=255;
		if(bc>255) bc=255;
		int r=fc+random.nextInt(bc-fc);
		int g=fc+random.nextInt(bc-fc);
		int b=fc+random.nextInt(bc-fc);
		return new Color(r, g, b);
}
%>
<%
		//设置页面不缓存

		response.setHeader("Pragma","No-cache");
		response.setHeader("Cache-Control","no-cache");
		response.setDateHeader("Expires", 0);
		
		// 在内存中创建图象
		int width=60, height=20;
		
		BufferedImage image = new BufferedImage(width, height, BufferedImage.TYPE_INT_RGB);
		
		// 获取图形上下文

		Graphics g = image.getGraphics();
		
		//生成随机类

		Random random = new Random();
		
		// 设定背景色

		g.setColor(getRandColor(200, 250));
		g.fillRect(0, 0, width, height);
		
		//设定字体
		g.setFont(new Font("Times New Roman",Font.PLAIN,18));
		
		//画边框

		g.setColor(new Color(255, 255, 255));
		g.drawRect(0, 0, width-1, height-1);
		
		// 随机产生155条干扰线，使图象中的认证码不易被其它程序探测到

		g.setColor(getRandColor(160,200));
		for (int i=0;i<155;i++) {
			int x = random.nextInt(width);
			int y = random.nextInt(height);
			int xl = random.nextInt(12);
			int yl = random.nextInt(12);
			g.drawLine(x,y,x+xl,y+yl);
		}
		
		// 取随机产生的认证码(4位数字)
		String sRand = "";
		for (int i=0; i<4; i++) {
			String rand=String.valueOf(random.nextInt(10));
			sRand+=rand;
			// 将认证码显示到图象中
			g.setColor(new Color(20 + random.nextInt(110), 20+random.nextInt(110), 20+random.nextInt(110)));
			//调用函数出来的颜色相同，可能是因为种子太接近，所以只能直接生成

			g.drawString(rand,13*i+6,16);
		}
		
		// 将认证码存入SESSION
		session.setAttribute("ACEGI_SECURITY_FORM_CAPTCHA_RESPONSE_KEY", sRand);
		
		// 图象生效
		g.dispose();
		
		// 输出图象到页面

		ImageIO.write(image, "JPEG", response.getOutputStream());
%>

